Process for sweetening hydrocarbon oils



Sept 22, 1953 J. H. KRAUSE PROCESS FOR SWEETENING HYDROCARBON OILS FiledDec. 27, 1950 Illr INVENTOR.'

JACK H. KRAUSE @M ATTOZEY:

Patented Sept. Z2,V 1953 PROCESS FOR SWEETENING HYDRocARBoN oILs Jack H.Krause, Hammond, Ind., assignor to Standard Oil Company, Chicago, Ill.,a corporation of Indiana Application December 27, 1950, Serial No.202,968

16 Claims. 1

This invention relates to an improved process for sweetening sour, i.e.y mercaptan containing, hydrocarbon oils. `More particularly, itrelates to the production of sweet, color stable oils which boil in therange of 300 F. to 650' F., such as, heavy naphtha, kerosene, dieseloil, furnace oil and heater oil; these oils are commonly known asdistillate fuels. Still more particularly, the invention is directed toan improved copper sweetening process.

One of the widely used processes for removing the sour odor present inmost naturally occurring hydrocarbon oils, especially those obtained bydistillation of crude' petroleum, is the socalled cupric chlorideprocess.- .This process is described in S. patents Re. 20,938 and2,042,051; and in more detail as to the coinrnercialV application in Oiland Gas Journal, March 22, 1947, page 195. It has been found that cupricchloride sweetened oil is not color stable, particularly at elevatedtemperatures. In the case of oils boiling within the gasoline range,this color instability is. easily overcome by the addition of very smallamounts of a copper metal deactivator. However, it has beenl found thatcopper-'metal deactivators are relatively ineffective to stabilize thecolor of oils in the heavier-than-gasoline boiling range. With oils fromsome crudes, such as West Texas,

the cupric chloride sweeteningI process produces a color` degradationsuch that the freshly sweetened oil is of unsatisfactory color.

copper sulfate or preferentially water soluble,`

copper sulfonates, supported on an inert carrier and containing at leasta certain minimum amount of water (about 8%) can be used to sweeten souroils when the treating is carried out at a temperature in excess ofabout k190" F. in the presence of free oxygen. My preferentially watersoluble copper sulfonates are selected from the group consisting ofVcopper alkane sulfonates, withA not more than ten carbon atoms'thereinand copper aryl sulfonates, with not more than la total of eight carbon.atems in Another object of an added copper metal deactivator.

The drawing which forms a part of this specication shows in schematicform one embodiment of a system for using my process.

This process "is applicable to any hydrocarbon oil containingmercaptans. It is particularly applicable to petroleum distillates Suchas naphthas, kerosene, diesel oil, furnace oil 2nd heater oil. Thedistillates in the heavier-than-gasoline boiling range are especiallysuitable for treatment by this process because of the difficulty thatexists in obtaining a color stable product when using the cupricchloride process. The following tests were made on a heater oildistillates obtained from West Texas crude and Mid- Continent ,crude andcharacterized as follows:

W. T. Acid W. T. Raw M. C. Raw

. Treated Dxstillate Distillate Distillate API Gravity 4o. s 4o, 9 41.5M ercnptan number 3 8 The W. T. acid treated distillate was obtained by-treating raw West Texas distillate with 8 pounds of 98% sulfuric acidper barrel of distillate, separating the sludge, coalescing out thesludge pepper, neutralizing the oil with caustic and water washing toremove traces of caustic.

In all tests, the initial color of the sweet oil was determinedimmediately after washing or after separation of the catalyst and thecolor stability was determined by the color after an accelerated test.In the accelerated test, 100 ml. ofthe sweet'oil in an open beaker aremaintained at 200 F. for 20 hours. A copper sweetened oil should have asatisfactory commercial storage color stability if its accelerated agedcolor is +10 Saybolt or better.

It has been` discovered that sweetening cannot be obtained `with coppersulfate or the preferentially water soluble copper sulfonates in theabsence of water. Best results were obtained when the catalyst consistedof the copper salt,

water and en inert adsorbent support, such as fullers earth, Attapulgusclay, silica gel, activated carbon, alumina, etc. The catalysts used inmy tests were made by adding the defined amount of Water to the coppersalt, then adding the defined amount of Attapulgus clay nes and stirringthe mass until the mixture was uniform. (All ingredients are on a weightbasis The catalyst was a free-flowing granular material up to a totalwater content of about 45 weight per cent based on total copper salt,solids land vvatergl above this water content the catalyst `lest 'itsfree-flowing granular form and became a muddy solid.

The copper salts are preferably used the hydrate crystal form but theanhydrous form can be used. The water of vhydration .of the crystalsmust be considered in determining the total water content of thecatalyst.

It has been found that either the C. P. grade or the commercial grade'of :copper'sulate can be used successfully. 'The .copper sultonate wereprepared 'by reacting copper carbonate with the sulfonic acid. Theparticular copper Valkarre sulfonate used in the example :set .outherein was obtained from a lmixed methane 1(130 'Volume per cent),ethane (50%), 2-propane (10%) fsulonic acid and the rest lepropane andisobutane sulfonic acids. (This `mixed alkanesulfonic 'acid was preparedVby the process disclosed In U. S.

2,433,395). It hes been found that the copper alkanesulfonatescontaining more than carbon atoms are so oil soluble that the catalyst.is rapidly destroyed. The copper arylsuli'onate's with more than eightcarbon atoms "in the alkyl substituents are too -oil soluble tor luse inthis process. I preferto use-copper benzenesuflstonate or coppertoluenesulfonate.Y

The tests were carried `out as follows: The foil, 500 ml., was heated tothe treating temperature in a flask equipped with a stirrer; the roilwas saturated with oxygen by air blow-ing; the lcatalyst, 6 volume percent based on oil, Was added to the oil and the mixture stirred forabout two minutes while the temperature was maintained at the desiredpoint. If the oil could be sweetened by the particular catalyst at thetemperature of treatment, two minutes contacting `was more than enoughtime to produce a sweet oil; with good agitation of the catalyst-oilmixture the sweetening reaction proceeds very rapidly. The mixture wasallowed ito settle for about 45 minutes and the treated oil separated.Usually the treated oil was washed with water, about one volume per twovolumes of oil,V although more or less Water can be used. The oil-watermixture was allowed to settle for about ten minutes. The oil wasdecanted off and the suspended and dis; solved water removed by Aa saltfilter. The temperature of the water washing 4operation is notimportant. It was found that for many oils, the water washing operationcould be eli-minated without adverse elect on color stability.

Eyect :of treating temperature The effect of temperature on the.sweetening of the sour oil was determined by using a catalystconsisting of: clay, 72 weight per cent; Water, Weight per cent; coppersalt, 8 Weight per cent. The Doctor test was used to determine are W. T.ACID TREATED 0IL Product Oil Treating Color Copper Salt Temper- ProductOil ature, F.

Initial Aged VSulfate l 150 sour Mixedlkanesulonate. 180 not quitesweet.. g Swzet..t 17 l3 5 no qui eswee m1uenesumM :1195 Sweet 22 19 M.G. OIL

sour 180 not quiteswect.. Sll'fate 20d, sweet 19 19 220 d 19 y, 122e dois i1 '.1805 sour v. MixedAlkarsulfonate 2200- not quiteswe l 22H7 sweetW T RAW'OIL isnl Sulfate l .20D .220.A 180 Mixed Alkenesulfonata 2(10 f..229. sweet.. 16 l0 l No .water-washngater thesweetening step.

The specic'ationsfor distillate fuels for domestic hea-ting uses.require :an :oil of yless than one rnercaptan number; by the Doctortest, this is equal to an oil that is not quite sweet. This process canproduce :a satisfactory oil in both sweetness and color .stability when.the reaction carried out -at about 190 F.; a completely sweet .oil is:obtainable by treating at about 200 F. With the very Worst oil, inregard to mercaptan content, a treating temperature of about 229 I'..should .result a 'satisfactory product.

Eect 'of water Vcontent The eieet of total water 'content of thecatalys-t on the sweetening of the sour 'oil was determin-ed by Vvaryingthe total water Ycontent and maintaining the weight ratio between theAclay and "copper `sulfate at 9 to 1.

W. T. .ACID TBEATED VOIL lsour `do. r

Vto obtain a sweet product.

The data on the effect of total water Vcontent influence on the minimumwater content needed to obtain a satisfactory product oil. Where the 3mercaptan number acid treated oil can be sweetened at about 190 F. withabout 8% water content, the mercaptan number oil needed a 20% watercontent at about 200 F.

Up to about 45 weight per cent water content the -catalyst is afree-flowing granular material; when more water is added, thefree-flowing granular structure disappears and the mixture is a muddysolid which cannot readily be incorporated intooil. The data on 43%water content show a marked degradationof the initial color of theproduct oil and, in the case of the very high mercaptan oil feed oil, anunsatisfactory Vaged color.

Eect of copper content Tests were made on the sweetening ability of thecatalyst when the total water content was held constant and the ratio ofclay to copper sulfate varied. No noticeable effect on the sweeteningability of the catalyst was observed between clay to copper salt ratiosof 12:1 and ratios of 3:1. When the clay to copper salt ratio is largerthan 12:1, the copper content is so slight that an undue length ofcontacting time is necessary When the ratio is less than 3:1, a sweetproduct can be produced but other detriment, such as poor product color.may be encountered.

Comparison with cuprzc chloride process Product Oil Color Initi;l AgedM. C. Oil 19 2. W. T. Raw Oil -4 4 N. P. AJ. 'W. T. Acid Treated Oil -i0 2 N. P. A.

W. T. Acid Treated Oil 2 -12 2% N. A.

l Sediment formed.

2 Treated at 220 F.

In all cases, a sweet product oil was obtained, but in no case did thecupric chloride process pro-Y duce a sweet oil of satisfactory colorstability. In the treatment of the high mercaptan sulfur West Texas'oil,the original distillate color of about 20 was degraded to below thesatisfactory point, 10 Saybolt color.

Referring to the drawing, the sour feed oil I0 should be free of eitherhydrogen sulfide or caustic. Ii the feed oil contains HzS, this can beremoved with a simple caustic wash. The feed oil is passed through arock salt filter in order to remove Vtraces of caustic remaining., inythe washed oil. From the salt filter Y|, the oil passes through line l2to heater l5 where its temperature is raised to between 190 F. to 230F., preferably about 200 F. It has been found that the hot oil removesthe water from the catalyst with rapid deactivation thereof and thatthis adverse action can be slowed down, if not prevented, by saturatingthe hot oil with water before the hot oil comes into contact with thecatalyst. Water,y

from a. source not shown, is passed by prepor- ,passes through line 40into reactor 4|.

tionatingpumprnthrough line I8v into heater |9, where the watertemperature is raised to about V200 F.l 'The hot water passes throughline 20 into line I6 where it enters the hot oil stream; only enoughwater to saturate thehot oil is added. Commercial oxygen, or air, isintroduced into the water saturated hot oil stream through line -22; theoxygen addition is dependent on the mercaptan content of the sour oil.Each 0.01 per cent -of mercaptan sulfur requires about 0.10 cubic :feetvof oxygen per barrel of sour oil. The combined 'stream then passes intomixer 25 where the oxygen is finely dispersed throughout the hot oil andany water droplets are broken up and are l,dissolved in the hotoil.The'water-saturated,-

oxygen-rich oil-stream passes by line 26 to pump 21 and on into line 30.

In slurry tank 32, the catalyst, which preferpumpable slurry with anamount of hot oil obtained from line |6 by way of line 34. Thecatalyst-oil slurry is forced by pump 36 through line 31 into line 30where the catalyst meets the hot sour oil stream. The hot oil-catalyststream Reactor 4| is a cone-bottom vessel; here the catalyst settles outof the sweet (or not quite sweet) oil. The catalyst is withdrawn fromthe reactor 4| by line 42 and may be discharged from the system throughvalved spent catalyst line 44. The oil passes from the reactor by line41. Water is introduced from line 48 into line 41 and the wateroilstream is thoroughly intermingled in mixer 50. The purpose of this Waterintroduction is to remove particles of copper sulfate and fullers earththat are suspended in the sweet oil. The amount of water used may varyfrom 25 to 100 .volumes per volumes of oil, with about 50 volyurnespreferred. The water-oil stream passes .from mixer 50, through line 5|into settler 52.

'I'he wash water is withdrawn from settler 52 through line 53 to thesewer or it may be recycled to line 48 or to pump l1, if desired. Thewashed oil leaves settler 52 through line 55 and passes lthrough cooler56 where its temperature is reduced to about ambient temperature. Thecooled ,oil is passed through salt filter 58 to remove water and emergestherefrom as product oil and goes V by line 59 to storage (not shown).

It has been observed that sour oils having a mercaptan number above 0cause a rapid deactivation of the catalyst even though theV oiltheoretically contains enough oxygen to regenerate the catalyst. It isbelieved that the deactivation is primarily due to the dehydration ofthe cata- -lyst by the hot oil. This eiect can be overcome to someextent by saturating the hot oil with water before the oil contacts thecatalyst. Also, the catalyst itself can be revivied by addition of-water to the spent catalyst-oil slurry and con- .tacting this withoxygen. By the use of these expedients, the life of the catalyst can beprolonged and the catalyst may be recycled instead of being discarded.Thus, if the oil feed is a '10 mer- ;captan number West Texas heater oildistillate,

fslurrypassesthro'uh mixer l'68 "wherefthe ireviyie cation' iscompleted; thereviviedcatalys't passes 'through Iline `-10 into feductorY'H which is located on "a valv'ed byp'a's's of line f40. vThe eductor'l-I causes the `fl`o`w through line 6-2, imiXer '63 and line 10. yThestream in line 'l0 'mixes with the vhot sour 4oil and Ymake-up from theslurry tank 32 `and passes `the mixture through line fl!) into reactor4l.

y When the sour -oil can be made into a product loil of satisfactorycolor stability without water washing, the washing step can beeliminated and the oil from'reactor v4I sent directly to cooler 56 l-b'yline 15. Other modifications and alternative 4operating procedures willbe apparent from the above description to those skilled in the art.

I claim:

`|1. process '-'for sweetening mercaptan-#conmtaining hydrocarbon oilswhich comprises intimately Vcontacting said oil, in the liquid state,with la 'catalyst consisting of Ian inert adsorbent material, a coppersalt and at least about 8 weight per 'cent' of wat-er, ata temperaturebetween about 190 F. and 230 F., and in the presu k'ence or free-oxygen,wherein said lcopper salt is selected 'from the group consisting ofvcopper sul;- fate and `prefere'ntially water soluble lcopper sul-'fon'ates 2. A process for sweetening lsour petroleum loils whichVcomprises intimately contacting said oil, the liquid state, in thepresence of free-oxygen, at a temperature between about 190 F. 'and 230v1d". with a catalyst consisting of about 8 to 45 weight per cent water,and an inert adsorbent material and 'a copper salt in the ratio, on aweight basis, o'f between about 12:1 and 3:1, wherein said copper saltis selected from the group consisting of copper Vsulfate andpreferentially water soluble copper sulfonates.

Y3. The .process of claim 2 where the treating temperature is from about200 F. to 220 F.

4. The process of claim 2 wherein the copper -salt is copper sulfate.

5. The .process o1 clairn 2 Where 'the copper saltV is a copperalk-anesulfonate containing notr more than '10 carbon atomsfpermolecule.

6. The Aprocess of 'claim 2 ,where the copper salt is fa copperaryls'ulfonate containing not .more than l8 carbon atoms in any alkylsubstituent.

'1. The process of claim 2 where the copper salt is prepared from amixed alkanesulfonic acid consisting oi methane sulfonic acid about 30volume percent, ethanesulfonic acid about 50 Volume percent, propanesulfonic acid about 10 volume percent and the remainder, butano sulfonicacids.

8. The process of claim 2 wherein the copper salt is copper toluenesulfonate.

9. A process -tor sweetening sour petroleumoils having a mercaptannumber of less than about 10 which comprises intimately contacting saidsour oil in the liquid phase with a sweetening catalyst consisting of aninert adsorbent material and a copper salt, .in a weight ratio between12:1 and 3:1J and water, between 8 and Ll() weight per cent, in thepresence of a free-oxygen containing f'gas esistere between-fz'oo'rian'd 220i F.

and separa 'iig the :sweetened oil ironi said catalyst, wherein thecopper salt in said 'Sweetehing catalyst lis 'selected from 'the y'groupconsisting of copper s'iilfate 'and preferentially water soluble -theliquid sourcil with a sweeten'ing catalyst consisting of an Yinertadsorbent material and a copper "salt, inea Weight 'ra'to between 12:1and and 3:-1, and about 20 weight per cent water in the presence orafree-oxygen con-tain gas `at a temperature between 200 F. land "220separating the sweetened oil from ysaid catalyst and water washing saidl'sweetened oil, wherein the copper salt in said sweete-ning catalyst isselected from the `grou-p consisting-.of copper sulfate andpreferentially water soluble copper sulionates.

11.v A 'process for making a sweet, color stable distillate fuel -iro'ma sour petroleum oil which process comprises intimately contacting saidsour oil in the liduid phase in the presence oi freeoxygen at atemperature between 200 and 229 withra sweetening 'catalyst consistingof '60 to 'Z5 weight per cent'inert adsorbent material, 5 to 20 weightper cent 4of ya copper salt. and about 20 weight percent of water, andseparating said catalyst from the sweetened oii, wherein said coppersalt is selected from the `group consisting of copper sulfate andpreferentially water soluble copper 4sulfonates. Y

12. The processor claim 11 wherein the copper salt is 'copper sulfate.

13. The process 'of claifr'i 11 'wherein the copper salt Vi's prepared"from a mixed alkanesulfonic acid consisting o1 methane sulfonic acidabout 30 Volu'r'n'e percent, 'ethane sulcnic acid` about 50 volumepercent, propane sulonic acid about l0 volume percent and the remainder,butane sul- -fon-ic acids.

14. The process 'of claim 11 wherein the copper salt is copper toluenesulfonate.

15. The process of claim 11 wherein the sweetened oil from theseparating step 'is washed with Water.

16. rThe process of claim 11 wherein the sweetening catalyst consists ofabout 12 weight per cent fullers earth, about 8 weight per cent coppersulfate Yand about 2O Weight per cent water.

JACK H. KRA'USE.

References Cited in the iile of this patent 'Nrinh STATES PATENTS NumberName Date 2,094,485 Buell Sept. 28, 1937 2,111,487 Chaney et al. N/ar.15, 1938 2,204,234 Schulz June 11, 1940 2,297,650 Fry et ail. Sept. 2Q,1942 2,338,371 Workman Jan. 1944 2,539,808 Brooner Jan. 30, 19512,593,464 Krause Apr. 12, 1952

1. A PROCESS FOR SWEETENING MERCAPTAN-CONTAINING HYDROCARBON OILS WHICH COMPRISES INTIMATELY CONTACTING SAID OIL, IN THE LIQUID STATE, WITH A CATALYST CONSISTING OF AN INERT ADSROBENT MATERIAL, A COPPER SALT AND AT LEAST ABOUT 8 WEIGHT PER CENT OF WATER, AT A TEMPERATURE BETWEEN ABOUT 190* F. AND 230* F., AND IN THE PRESENCE OF FREE-OXYGEN, WHEREIN SAID COPPER SALT IS SELECTED FROM THE GROUP CONSISTING OF COPPER SULFATE AND PREFERENTIALLY WATER SOLUBLE COPPER SULFONATES. 